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A mechanician that I know told me that the damage on the inside lip (extra rubber inside, not the bead) of the tire like the image below is normal and often happens when mounting/unmounting tires each year.
The tire is fine (holding air correctly) and the guy who told me that is not the one who did this damage.
Question is: Does this kind of damage is normal or it should not really happen with modern equipment and a good technician?
Note that this is run-flat tires, which are more stiff.
Thanks
Unfortunately damage like this is very common. This damage normally happens when the tire is being dismounted. The bead of the tire has steel chords inside it so it can't stretch. To mount the tire the rim has a narrow spot in the middle. This narrow spot allows the bead to be worked on and off by allowing one side to slip into the narrow spot and the other to slip over the edge of the rim.
In low profile tires getting the second bead pushed down until it's at the level of the narrow spot is very difficult. This can put extra strain the the inside edge of the bead at the opposite side. When mounting the tire the bead is pushed down form the top making it difficult to damage. When dismounting the bead is pulled up from underneath making the bead extra vulnerable. If using equipment that is not specifically designed for low profile tires or having a poorly trained technician will result in this damage. Unfortunately I have personally caused this same damage so no one is immune, but it is avoidable/preventable.
If the rim is clean and the tire is not severely damaged it should be just fine.
